Discovery of a redshifted X-ray emission line in the symbiotic
neutron star binary 4U 1700+24

Tiengo, A.; Salvo, T. Di; Méndez, Mariano; Miller, J. M.; Sokoloski, J. L.; Klis, M. van der

doi:10.1051/0004-6361:20035742

Cited by 15 publications

(35 citation statements)

References 21 publications

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“…The SyXB subclass only started gaining some attention from the scientific community in the last decade only; however, X-ray studies of these sources are still quite sporadic, with only a handful of objects having been explored in this spectral window (Masetti et al 2002(Masetti et al , 2007aRea et al 2005;Paul et al 2005;Tiengo et al 2005;Mattana et al 2006;Patel et al 2007;Corbet et al 2008;Marcu et al 2011;González-Galĺan et al 2012). …”

Section: Introductionmentioning

confidence: 99%

“…After this study, Tiengo et al (2005) published a paper on the X-ray behaviour of 4U 1700+24: the authors analysed an observation collected with the XMM-Newton satellite in 2002 and found an emission feature at ≈0.5 keV and an emission line at 0.64 keV which was possibly identified as the red-shifted O VIII Ly-α transition.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper we present an analysis of these data, together with an independent examination of the 2002 observation first reported by Tiengo et al (2005) in order to have a uniform analysis of the whole XMM-Newton and Swift/XRT data sets concerning 4U 1700+24. We found that the feature observed at 0.5 keV is possibly an artifact due primarily to the instrumental oxygen edge (see e.g.…”

Section: Introductionmentioning

confidence: 99%

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The puzzling symbiotic X-ray system 4U1700+24

Nucita¹,

Stefanelli²,

Paolis³

et al. 2014

A&A

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Context. Symbiotic X-ray binaries form a subclass of low-mass X-ray binary systems consisting of a neutron star accreting material from a red giant donor star via stellar wind or Roche lobe overflow. Only a few confirmed members are currently known; 4U 1700+24 is a good candidate as it is a relatively bright X-ray object, possibly associated with the late-type star V934 Her. Aims. We analysed the archive XMM-Newton and Swift/XRT observations of 4U 1700+24 in order to have a uniform high-energy (0.3−10 keV) view of the source. Apart from the 2003, 2010, and 2012 data, publicly available but still unpublished, we also took the opportunity to re-analyze a set of XMM-Newton data acquired in 2002. Methods. After reducing the XMM-Newton and Swift/XRT data with standard methods, we performed a detailed spectral and timing analysis. Results. We confirmed the existence of a red-shifted O VIII Ly-α transition (already observed in the 2002 XMM-Newton data) in the high-resolution spectra collected via the RGS instruments. The red-shift of the line is found in all the analysed observations and, on average, it was estimated to be 0.009. We also observed a modulation of the centroid energy of the line on short time scales (a few days) and discuss the observations in the framework of different scenarios. If the modulation is due to the gravitational red-shift of the neutron star, it might arise from a sudden re-organization of the emitting X-ray matter on the scale of a few hundreds of km. Alternatively, we are witnessing a uni-polar jet of matter (with typical velocity of 1000−4000 km s −1 ) possibly emitted by the neutron star in an almost face-on system. The second possibility seems to be required by the apparent lack of any modulation in the observed X-ray light curve. We also note also that the low-resolution spectra (both XMM-Newton and Swift/XRT in the 0.3−10 keV band) show the existence of a black-body radiation emitted by a region (possibly associated with the neutron star polar cap) with typical size from a few tens to hundreds of meters. The size of this spot-like region reduces as the overall luminosity of 4U 1700+24 decreases.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The puzzling symbiotic X-ray system 4U1700+24

Nucita¹,

Stefanelli²,

Paolis³

et al. 2014

A&A

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“…Its X-ray spectrum is also variable in the long term. A high-resolution X-ray spectroscopy analysis of 4U 1700+24 during a phase of enhanced activity was performed with XMM-Newton by Tiengo et al (2005).…”

Section: Introductionmentioning

confidence: 99%

M-typegiants as optical counterparts of X-ray sources 4U 1700+24 and 4U 1954+319

Masetti¹,

Orlandini²,

Palazzi³

et al. 2006

A&A

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We observed with Chandra two peculiar galactic X-ray sources, 4U 1700+24 and 4U 1954+319, which are suspected to have a M-type giant star as optical counterpart, in order to get a high-precision astrometric position for both of them. The peculiarity of these sources lies in the fact that these are the only two cases among low-mass X-ray binaries (LMXBs), besides the confirmed case of GX 1+4, for which the companion can possibly be a M-type giant. We found that in both cases the field M-type giant star is indeed the counterpart of these X-ray sources. We also determined the distance to 4U 1954+319 to be ∼1.7 kpc. This result suggests that a number of faint (L X ∼ 10 32 −10 34 erg s −1 ) Galactic X-ray sources are "symbiotic X-ray binaries", that is, wide-orbit LMXBs composed of a compact object, most likely a neutron star, accreting from the wind of a M-type giant.

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“…By analogy with the symbiotic stars, which are systems composed of an M-type giant and a white dwarf (WD), these LMXBs are sometimes referred to as "symbiotic X-ray binaries". The protoype of this small subclass, the system GX 1+4, is a wellstudied case (e.g., Chakrabarty & Roche 1997); the second member, object 4U 1700+24, is now receiving more attention Appendix is only available in electronic form at http://www.aanda.org (Masetti et al 2002(Masetti et al , 2006aGalloway et al 2002;Tiengo et al 2005).…”

Section: Introductionmentioning

confidence: 99%

X-ray broad-band study of the symbiotic X-ray binary 4U 1954+31

Masetti¹,

Rigon

Maiorano

et al. 2006

A&A

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We present results of several pointed X-ray broad band observations of the "symbiotic X-ray binary" 4U 1954+31 performed with the satellites BeppoSAX, EXOSAT, ROSAT, RXTE and Swift between October 1983 and April 2006. We also studied the RXTE ASM data over a period of more than 10 years, from January 1996 to October 2006. Light curves of all pointed observations show an erratic behaviour with sudden increases in the source emission on timescales variable from hundreds to thousands of seconds. There are no indications of changes in the source spectral hardness, with the possible exception of the RXTE pointed observation. Timing analysis does not reveal the presence of coherent pulsations or periodicities either in the pointed observations in the range from 2 ms to 2000 s or in the long-term RXTE ASM light curve on timescales from days to years. The 0.2−150 keV spectrum, obtained with BeppoSAX, is the widest for this source available to date in terms of spectral coverage and is well described by a model consisting of a lower-energy thermal component (hot diffuse gas) plus a higher-energy (Comptonization) emission, with the latter modified by a partially-covering cold absorber plus a warm (ionized) absorber. A blackbody modelization of our BeppoSAX low-energy data is ruled out. The presence of a complex absorber local to the source is also supported by the 0.1−2 keV ROSAT spectrum. RXTE, EXOSAT and Swift X-ray spectroscopy is consistent with the above results, but indicates variations in the density and the ionization of the local absorber. A 6.5 keV iron emission line is possibly detected in the BeppoSAX and RXTE spectra. All this information suggests that the scenario that better describes 4U 1954+31 consists of a binary system in which a neutron star orbits in a highly inhomogeneus medium, accreting matter from a stellar wind coming from its optical companion, an M-type giant star.

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Discovery of a redshifted X-ray emission line in the symbiotic neutron star binary 4U 1700+24

Cited by 15 publications

References 21 publications

The puzzling symbiotic X-ray system 4U1700+24

The puzzling symbiotic X-ray system 4U1700+24

M-typegiants as optical counterparts of X-ray sources 4U 1700+24 and 4U 1954+319

X-ray broad-band study of the symbiotic X-ray binary 4U 1954+31

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